Transmission electron microscopy (TEM) is an effective and versatile tool for the structural and chemical characterization of condensed matter at the nanoscale. TEM is applicable for an ample choice of studies, from resolution at the atomic level (known as ultra-high resolution-TEM) to the identification of atomic species and their valence states (known as electron energy loss spectroscopy), or the possibility for carrying out in-situ experiments within a controlled environment within sophisticated holders. Furthermore, the technique provides detailed information on the structure of materials during transformation and its correlation with their magneto-electrical properties. In situ TEM techniques comprise a broad spectrum of topics ranging from liquid and gas environmental TEM, three and four dimensional TEM, nanomechanics, switching of ferroelectrics domains and atomic imaging of light elements. With the advent of recent progress in instrumentation, such as aberration-corrected optics, sample environmental control, and significantly improved data acquisition techniques, the potential for TEM studies has been pushed further with enhanced resolution and the possibility for characterizing physical-chemical properties on an atomic-basis level. In this context, the conventional capabilities of TEM operational modes (diffraction contrast, phase contrast, and electron diffraction) have been expanded by cutting-edge techniques such as electron holography and precession-assisted diffraction.
The knowledge of the electromagnetic properties of materials at the nanoscale level has been made possible through analytical TEM techniques such as electron holography. This powerful technology uses the interference effect of the electron wave to detect and quantify the electromagnetic field of condensed matter at the nanometer scale and enables accurate characterizations of nanosized materials interacting with magnetic and electric fields. In particular, the resolution of the magnetic flux within nanoscale materials is a promising method to gain further physical insight into the magnetic domain formation and magnetization processes of nanoscale magnetic materials, such as magnetic nanowires, rendered as potential alternatives for significant enhancement of magnetic recording media technologies. This enables not only the physical characterization of the magnetic lenses of an electron microscope but also the in-situ analysis of the nanomaterial under study. In this context, a central issue for in-situ TEM studies in the magnetization response of nanomaterials by electron holography is the controlled application of a magnetizing field by using the objective lens (an electromagnetic lens) of the electron microscope as a magnetic field source. In such applications, the proper calibration of the magnetic field for the set of magnetic lenses within the electron microscope is critical in order to establish the effect of such magnetizing flux on the inner magnetization of the material, its magnetic domain configuration, and its magnetization dynamics.
When calibration of the magnetic field generated in the objective lens of an electron microscope is required, specific configurations and designs should be accomplished. For instance, the magnetic lenses in an electron microscope are manufactured using magnetic coils and their power depends on their capacity to increase applied voltage that is associated with the magnification of the electron microscope. There is a direct relationship between the voltage applied and the magnetic field produced, with the higher the voltage, the stronger the magnetic field that is produced. Few works have been reported in the literature for the calibration of the magnetic field within electron microscopes. Although calibration methods have been proposed, some can only be performed after disassembling the electron microscope. Disassembly is time consuming and must be performed very carefully to avoid damaging the critical components of the microscope. Needed is a system and method for in-situ measurement of the magnetic fields while the microscope is still in its fully assembled form.